Open joints, blocks out of line, soft ground behind the wall: the fill is washing out. We find the void, repoint or rebuild with proper drainage. We need to know which shore, wall type and length; photos help. Swansea Channel walls take tidal current and swell; lake walls take chop and boat wash. Tell us what yours is doing.
Get a Quote →Seawalls hold the land behind them back from wave action, boat wash and rising lake levels, and most failures start behind the wall rather than in front of it. Lake Macquarie is Australia's largest coastal saltwater lake, and its shoreline behaves differently to an ocean seawall — wave energy is generally lower, but the lake's tidal exchange through Swansea Channel, wind fetch running across the open stretches of the lake onto shores like Wangi Wangi and Mannering Park, and decades of boat wash in built-up areas like Belmont and Warners Bay all steadily wash fine backfill material out through ageing walls.
A proper repair starts with checking how much backfill has actually washed out behind the visible wall face, then either repointing sound sections or rebuilding failed ones with correct weep holes, geotextile filter fabric and backing drainage so the wall doesn't just fail again in the same way a few years later.
Full or partial rebuilds of collapsed or badly failed sections, in rock revetment, precast concrete panel or block wall systems suited to lake conditions.
Open mortar joints and small gaps sealed before they let enough backfill wash out to threaten the whole wall.
Backfill voids behind the wall identified and refilled properly, common along older walls in Belmont, Swansea and Toronto.
Structural assessment reports for council approval before repair or rebuild work goes ahead on lakefront foreshore.
We start behind the wall, at low water. We probe the fill for voids and look for daylight through the joints, because a face can look straight and still be hollow behind. Rain, wave run-up and a high lake all push water into the backfill. When the level drops that water has to get out, and through an open joint it takes the fines with it. So we pack the void with compacted fill, set weep holes just above normal water level with a gravel pocket or filter fabric behind each to hold the fines back, then seal the joints. On a rebuild the fabric goes against the fill, a drainage layer sits behind the face and the weeps drain that layer, so the wall sheds water without shedding ground.
How hard water works at those joints depends on where the wall is. Lake Macquarie City Council's 2013 Foreshore Stabilisation and Rehabilitation Guideline noted that tidal movement in the lake is restricted by the narrow ocean entrance at Swansea, with a maximum tidal range of about 0.2 m. It named three main causes of foreshore erosion: wind-generated waves, boat waves and wind-generated currents. Council's 2023 Coastal Management Program (CMP) adds that waves more than a metre high are not uncommon on the lake. At Belmont, Toronto or Wangi Wangi that means chop and boat wash, and drainage behind a sound face is most of the answer.
Swansea Channel is a different job. The CMP gives a tidal range of 1.7 m at the entrance, 1.3 m at Swansea Bridge and less than 0.2 m at the channel's western end. Seaward of the bridge, ocean swell comes in through the entrance breakwaters, which is what a wall at Swansea Heads or Blacksmiths faces. On the lake side, tidal currents dominate, and the CMP records that faster flow and scour there have caused foreshore protection works to fail. It attributes the sudden collapse of the Pelican Marina complex in February 2016 to erosion from the channel's ongoing migration. On a channel wall we look at the toe first. Current scours the bed, the toe drops and the face follows, so it needs a deeper toe and heavier rock than a lake wall usually does.
The paperwork follows the water line too. In the Lake Macquarie City Council area, the Development Control Plan 2014 (Part 9) requires a Visual Impact Statement with every foreshore development application, plus an Aquatic Habitat Assessment by a suitably qualified consultant for any development below mean high water. The DCP fixes that line at +0.132 m AHD (Australian Height Datum), so a survey of your frontage can show whether the work falls below it. A wall toe often sits below that line, so find out before the rock arrives.
We take seawall and revetment enquiries for Swansea Channel frontages at Swansea, Swansea Heads, Blacksmiths and Pelican, and for lake frontages at Belmont, Warners Bay, Toronto, Rathmines, Wangi Wangi, Mannering Park and Chain Valley Bay. The 2023 Coastal Management Program lists both Lake Macquarie and Central Coast councils among the lake's foreshore managers, so check which council and which land manager covers your frontage before lodging anything. If your wall is somewhere else on the lake, say where in your enquiry.
Tell us what you need and where the property is.